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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.66: Poster
Donnerstag, 26. März 2009, 15:00–17:30, P2
Excited state spectroscopy of single laterally coupled InGaAs quantum dot molecules — •Matthias Heldmaier1, Claus Hermannstädter1, Marcus Witzany1, Wolfgang-Michael Schulz1, Marcus Eichfelder1, Robert Rossbach1, Michael Jetter1, Lijuan Wang2, Armando Rastelli3, Oliver Schmidt3, and Peter Michler1 — 1Institut für Halbleiteroptik und Funktionelle Grenzflächen, Allmandring 3, 70569 Stuttgart — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart — 3Institut für Integrative Nanowissenschaften, IFW Dresden, Helmholtzstr. 20, 01069 Dresden
The investigated structures contain self-assembled laterally coupled InGaAs quantum dots embedded in a planar microcavity, which are grown using a combination of metal-organic vapor phase and molecular beam epitaxy. The individual quantum dot molecules (QDMs) consist of two single dots that are coupled along the [1-10] crystal direction via electron tunneling. The coupling strength and the ground and excited state energies of the QDMs can be manipulated applying a lateral electric field. A change in the relative intensities of the excitonic emission lines is observed in the photoluminesence (PL) spectra. PL excitation measurements were conducted using a wide-range tunable Ti:sapphire laser to obtain spectra of the excited QDM states as a function of electric field tuning. Pumping an excited exciton state (p-shell) at increasing pulse amplitudes leads to oscillatory behavior in the detected excitonic s-shell recombination. Special pulse amplitudes (π/2, π, etc.) can be extracted and used for subsequent coherent experiments.